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boiler service, boiler repair, emergency repair
Vaillant ecoTEC plus 838(VUW GB 386/5-5) Boiler Fault Codes
| Code | Meaning | Cause |
| F00 | Flow temperature sensor interruption | NTC plug not plugged in or has come loose, multiple plug on the PCB not plugged in correctly, interruption in cable harness, NTC defective |
| F01 | Return temperature sensor interruption | NTC plug not plugged in or has come loose, multiple plug on the PCB not plugged in correctly, interruption in cable harness, NTC defective |
| F02 | Interruption cylinder charging sensor actoSTOR (NTC) only in combination with F91 | NTC defective, NTC cable defective, defective plug connection on NTC, defective plug connection on actoSTOR electronics |
| F03 | Interruption cylinder sensor actoSTOR (NTC) only in combination with F91 | NTC defective, NTC cable defective, defective plug connection on NTC, defective plug connection on actoSTOR electronics |
| F10 | Flow NTC short circuit | NTC defective, short circuit in cable harness, cable/casing |
| F11 | Return NTC short circuit | NTC defective, short circuit in cable harness, cable/casing |
| F12 | Short circuit at cylinder charging sensor (NTC) only in combination with F91 | NTC defective, short circuit in cable harness, cable/casing |
| F13 | Product with integrated hot water generation: Short circuit warm start sensor/cylinder sensor Product with integrated hot water generation and actoSTOR: Short circuit cylinder sensor (NTC) only in combination with F91 | NTC defective, short circuit in cable harness, cable/casing |
| F20 | Safety switch-off: Temperature limiter | Incorrect earth connection between cable harness and product, flow or return NTC defective (loose connection), black discharge via ignition cable, ignition plug or ignition electrode |
| F22 | Safety switch-off: Low water pressure | No or insufficient water in the product, water pressure sensor defective, cable to pump or water pressure sensor loose/not connected/defective |
| F23 | Safety switch-off: Temperature difference too great | Pump blocked, insufficient pump output, air in product, flow and return NTC connected the wrong way round |
| F24 | Safety switch-off: Temperature rise too fast | Pump blocked, insufficient pump output, air in product, system pressure too low, non-return valve blocked/incorrectly installed |
| F25 | Safety switch-off: Flue gas temperature too high | Break in plug connection for optional flue gas safety temperature limiter (STB), break in cable harness |
| F26 | Fault: Gas valve without function | Gas valve stepper motor not connected, multiple plug on the PCB not plugged in correctly, interruption in cable harness, gas valve stepper motor defective, electronics defective |
| F27 | Safety switch-off: Flame simulation | Moisture on the electronics, electronics (flame monitor) defective, gas solenoid valve leaking |
| F28 | Failure during start-up: Ignition unsuccessful | Gas meter defective or gas pressure monitor has triggered, air in gas, gas flow pressure too low, thermal isolator device (TAE) has triggered, condensate duct blocked, incorrect gas restrictor, incorrect spare part gas valve, fault on the gas valve, multiple plug on PCB incorrectly plugged in, break in cable harness, ignition system (ignition transformer, ignition cable, ignition plug, ignition electrode) defective, ionisation current interrupted (cable, electrode), incorrect earthing of product, electronics defective |
| F29 | Failure during operation: Re-ignition unsuccessful | Gas supply temporarily stopped, flue gas recirculation, condensate duct blocked, defective earthing of product, ignition transformer has spark failure |
| F32 | Fan fault | Plug on fan not correctly plugged in, multiple plug on PCB not correctly plugged in, break in cable harness, fan blocked, Hall sensor defective, electronics defective |
| F42 | Coding resistance fault (possible in combination with F70) | Short circuit/interruption in output range coding resistance (in cable harness at heat exchanger) or gas group resistor (on PCB) |
| F49 | Fault: eBUS | Short circuit on eBUS, eBUS overload or two power supplies with different polarities on the eBUS |
| F52 | Contact fault mass flow sensor/Venturi |
The mass flow sensor/Venturi is not connected electrically – The plug is not plugged in correctly – The plug is not plugged in – The plug is defective – The slot is defective (loose connection) – Mass flow sensor/Venturi defective |
| F53 | Combustion regulation fault |
The mass flow sensor/Venturi is not connected electrically – The plug is not plugged in correctly – The plug is not plugged in – The plug is defective – The slot is defective (loose connection) – Mass flow sensor/Venturi defective |
| F54 | Fault in the gas supply (in combination with F28/F29) |
There is insufficient gas supply to operate the unit – Gas isolator cock(s) closed – Gas flow pressure is too low – Gas valve defective |
| F56 | Combustion component fault |
A component in the combustion regulation is defective – Contact fault at the gas valve (plug not plugged in correctly or not plugged in, plug defective, slot is defective (loose connection)) – Natural gas coding resistance used when operating with liquid gas – If the fault occurs again after being cleared: The gas valve is defective |
| F57 | End comfort protection mode |
Active comfort protection mode has detected a regulation fault – Ignition electrode highly corroded |
| F61 | Gas valve actuation fault |
The gas valve cannot be actuated – Cable harness supply line to the gas valve is defective (short to earth, short circuit) – Gas valve defective – PCB defective |
| F62 | Gas valve switch-off delay |
Delayed shutdown of gas valve detected – Secondary light (ignition and monitoring electrode indicates delayed extinguishing of the flame signal) – Gas valve defective – PCB defective |
| F63 | Fault: EEPROM | Electronics defective |
| F64 | Fault: Electronics/NTC | Flow or return NTC short circuited, electronics defective |
| F65 | Fault: Electronics temp | Electronics overheating due to external influences, electronics defective |
| F67 | Fault: Electronics/flame | Implausible flame signal, electronics defective |
| F68 | Fault: Unstable flame signal | Air in gas, gas flow pressure too low, incorrect air ratio, condensate duct blocked, incorrect gas restrictor, ionisation flow interruption (cable, electrode), flue gas recirculation, condensate duct |
| F70 | Invalid device specific number (DSN) | If spare parts fitted: Display and PCB replaced at same time and DSN not reset, incorrect or missing output range coding resistance |
| F71 | Flow NTC fault |
Flow temperature sensor signalling constant value: – Flow temperature sensor incorrectly positioned at supply pipe – Flow temperature sensor defective |
| F72 | Flow/return NTC fault | Flow/return NTC temperature difference too great → flow and/or return temperature sensor defective |
| F73 | Water pressure sensor signal in the wrong range (too low) | Interruption/short circuit of water pressure sensor, interruption/short circuit to GND in supply line to water pressure sensor or water pressure sensor defective |
| F74 | Water pressure sensor signal outside correct range (too high) | Line to water pressure sensor has a short circuit to 5 V/24 V or internal fault in the water pressure sensor |
| F75 | Fault: No pressure change detection when starting pump | Water pressure sensor and/or pump defective, air in the heating installation, insufficient water in the product; check adjustable bypass, connect external expansion vessel to the return |
| F77 | Fault: Flue non-return flap/condensate pump | No response from flue non-return flap or condensate pump defective |
| F78 | Interruption to DHW outlet sensor at the external controller | UK link box is connected, but hot water NTC not bridged |
| F80 | Interruption or short circuit of secondary heat exchanger inlet sensor; only in connection with F91 | NTC defective, NTC cable defective, defective plug connection on NTC, defective plug connection on actoSTOR electronics Sensor plug has short to earth to the casing, short circuit in cable harness, sensor defective |
| F81 | actoSTOR charging pump defective; only in combination with F91 |
Cylinder is not fully charged after specified time. – Check cylinder charging sensor and cylinder sensor – Air in the actoSTOR pump – Inspect cable harness for pump – Check the impeller sensor and/or limiter in the product – Diverter valve defective – Secondary heat exchanger blocked – Pump faulty |
| F83 | Fault: Flow and/or return temperature sensor temperature change |
When the burner starts, the temperature change registered at the flow and/or return temperature sensor is non-existent or too small. – Insufficient water in product – Flow or return temperature sensor not in correct position at pipe |
| F84 | Fault: Flow/return temperature sensor temperature difference implausible |
Flow and return temperature sensors returning implausible values. – Flow and return temperature sensors have been inverted – Flow and return temperature sensors have not been correctly installed |
| F85 | Fault: Flow and return temperature sensors incorrectly installed | The flow and/or return temperature sensors have been installed on the same pipe/incorrect pipe |
| F90 | Communication with actoSTOR module interrupted | Check cable harness from product to actoSTOR module (PEBus). If the product is to be operated without an actoSTOR module, set D.092 = 0. |
| F91 | Sensor/actuator fault on actoSTOR module | |
| F92 | Coding resistance fault | The coding resistance on the PCB does not match the entered gas group: Check the resistance, repeat the gas family check and enter the correct gas group. |
| F93 | Poor combustion quality |
Combustion regulation has detected poor combustion quality – Incorrect gas restrictor has been installed for the gas family (another gas family is present) – Recirculation – Mass flow sensor/Venturi defective (wet, blocked): Do not wet the sensor, do not use any lubricants on the O-ring on the Venturi. |
| LED actoSTOR module | actoSTOR electronics status |
LED on: Communication OK LED flashing: Communication not OK LED off: No power supply |
| Communication fault | No communication with the PCB | Communication fault between display and PCB in the electronics box |